Apparatus for moving a radioactive source between exposure and safe positions



May 31, 1966 o. A. PETERSON APPARATUS FOR MOVING A RADIOACTIVE SOURCE BETWEEN EXPOSURE AND SAFE POSITIONS 2 Sheets-Sheet 1 Filed July 18, 1962 INVENTOR OSCAR A. PETERSON y 1966 o. A. PETERSON 3,254,224

APPARATUS FOR MOVING A RADIOACTIVE SOURCE BETWEEN EXPOSURE AND SAFE POSITIONS Filed July 18, 1962 2 Sheets-Sheet z INV ENT OR OSCAR A. PETERSON BY 420M United. States Patent This invention relates to apparatus for holding a radioactive source such as cobalt 60 in safety position deep within shielding, and provided with means for moving the source to a radiation position to permit emanation of radiation and also means for retracting the source to safety position, more particularly to such apparatus whereinthe radioactive material is attached to an actuating rod adapted to move within and in relationship to a shielded container, and especially to such apparatus wherein the actuating rod is adapted to move the radioactive source completely out of the shielding and into a receiving aperture which may be in the wall of a high pressure vessel or the like, the source being part of a radioactive radiation apparatus for measurement of level of material within the vessel.

Various radioactive radiation type means have been suggested for measurement of the level of material within a container, and they may involve having one or more sources of radiation on one side of the vessel and one or more detecting devices on the opposite side of the vessel. The intensity of radiation as received by the detecting device is related to the density of material through which the radiation passes; i.e. the intensity is higher ifit passes through a gas than if it passes through a liquid, so that as the liquid level builds up in a tank, there is a sharp change in detected intensity when the liquid level reaches the height of the radiating device. The art is confronted by the problem of shielding of radiation sources as well as providing an efiicient means for moving the source into a radiation position which may be deep within the wall of a thickwalled vessel, and also back into a safety or' shield-' ed position in case of an emergency; e.g., when there is interruption of a chemical process using the thick walled vessel as part of the apparatus therefor. In addition, it may be desirable to move the source into a safety position when personnel must be close to the vessel for maintenance or other reasons, or for replacement of the radiating device. r

The discoveries associated with the invention and relating to the solution of the above problems, and the objects achieved in accordance with the invention as set forth herein include the provision of:

An apparatus adapted to maintain a-radioactive source in a shielded safety position and also to move it to a radiation position to permit emanation of radiation including a mass of shielding material provided with a bore therethrough adapted to hold an actuating rod to which rod is attached a radioactive source, means for moving said rod in a position sothat the radioactive source is substantially in a center of said mass as well as for moving said rod so that said source is outside of said mass, a bore within said mass at substantially right angles to the above maintained bore and provided with a plug of similar shielding material within said bore;

Such an apparatus wherein the means for actuating the radioactive source is nonrotatable and it is adapted to be extended completely out of the source and into receiving aperture wherein it forms part of a level measuring device;

Such an apparatus wherein the plug is rotatable and is provided with a bore adapted to be aligned with the first bore; and also provided with rotating means adapted to turn it from a position where its bore is in alignment with the bore in the fixed mass in which the actuating means travels, to a position at a angle thereto;

Such an apparatus wherein said rotating means is a pneumatic arrangement including a piston and cylinder adapted to be actuated by compressed air;

Such an apparatus wherein the plug may be lifted way out of the bore;

Such an apparatus wherein the radioactive source actuating means is provided with pneumatic actuating source including a piston and cylinder assembly adapted to be actuated by compressed air;

Such an apparatus wherein the actuating rod is substan tially square in cross-section and travels in a bore at least a part of which is substantially square and is reasonably close fitting therein;

And other objects which will be apparent as details or embodiments of the invention are set forth hereinafter.

In the accompanying. drawing, FIGURE 1 is a substantially longitudinal-sectional View of one embodiment of the invention and FIGURE 2 is a cross-sectional view taken along line 2-2 of FIGURE 1, and FIGURE 3 is a similar view of another embodiment.

In order to indicate still more fully the nature of the present invention, the following examples of typical procedures are set forth and unless otherwise indicated it being understood that these examples are presented as illustrative only and they are not intended to limit the part scope of the invention.

Example 1 Referring to FIGURES l and 2 of the drawing, a thick wall of a high pressure separation vessel is represented "by 10a and this may be provided with a heat exchanger chamber made up of Walls 13. Such a vessel is shown in my application Serial No. 201,145 filed June 7, 1962, which issued on September 21, 1965 as Patent No. 3,207,214. The vessel is provided with an aperture 10 and a guide member12 suitably attached thereto. A shield made up of a steel or stainless steel container 14 loaded with lead 14a is provided with a square bore 15. It is also provide-d with a steel lined circular bore or well 17 and circular plug 18 which is made up of a steel shell and filled with lead. This plug is provided with a transverse bore 19. Attached to the plug is crank 20 which in turn is attached to rod 21. This rod is attached to piston 23 in cylinder 22. The cylinder is connected to a source of compressed air via lines 24 and 24a which are provided with valves 25 and 25a. end to the other of the cylinder the crank rotates the plug through a 90 angle. Actuating rod 31 having a square portion 31a is adapted to slide within square bore 15. This is connected to rod 31 which in turn is connected to piston 33 within cylinder 32. Attached to rod 31a is a radioactive source capsule 36 which may be removably attached by means of a threaded connection or by means of a sleeve or lock pin or set screw arrangement or equivalent means.

In operation, the plug 18 is rotated so that the bore 19 is in alignment with the bore 15, the Whole assembly being supported on a bracket or equivalent means (not shown) so that recess 37 fits over the flanged end of tube or guide 12. Upon movement of piston 33 to the right end of cylinder 32 by means of compressed air introduced via line 34 and valve 35, the radioactive source 36 is moved to position 11. Due to the square actuating rod and square bore 15 this source is placed in the same position upon repeated removals and reinsertions. To remove the source from position 11 back to safety position within the shield, compressed air is introduced into cylinder 32 via lines 34 and 34a and valve 35 a. Preferably the actuating rod 31a is a'hollow steel chamber filled with lead to provide shielding. After retracting the radioactive source 36 back to Upon movement of the piston from one the shielded position, the plug 18 is rotated through 90 to provide shielding and to hold the source within the chamber. This rotation is achieved by proper movement of piston 23, opposite to the movement which aligns bore 19 with bore 15.

Example 2 Referring to FIGURE 3, the rotatable plug of the above example is changed to the form of a plug 18a of any suitable cross-sectional shape, which is caused by pneumatic means (e.g., rod 41, piston 43, cylinder 42, and air line 44, with valve 44a, plus air line 45 and valve 45a) to retract from the well 17a provided in the shielding box 14ml; supporting pall 41a or equivalent mechanical means is also provided. In this variation, the plug is not provided with a transverse bore, since it is raised out of the path of the actuating rod. Upon return of the capsule to a center zone of the box, the plug is caused to lower into position to serve as shielding, by reversal of the above movement. Other retracting means may be used.

Instead of a square actuating rod and a square bore, other equivalent means may be used. The rod may be non-circular or if circular may be provided with a slot or groove or other means adapted to contact a fixed means for preventing rotation. The cross-section may be triangular, rectangular or any other convenient shape. The radioactive unit is mounted in fixed relationship to the capsule, and the capsule is attached to the actuating rod so that its orientation relative to the radiation path is constant. This arrangement assures that no change in intensity of signal to the detector will be caused by repeated mechanical working of the apparatus, thereby avoiding or minimizing requirement of recalibration of the liquid level assembly, or equivalent device.

Although pneumatic means of actuating the device is preferable, other means may be used including manual, hydraulic, mechanical or any combination thereof. Instead of a substantially straight actuating means, curved means may be used and this may travel in part through a curved path within the shield. The actuating connection may be through a flexible wire or rod or through an atticulated means made up of a chain of links suitably connected to produce the nonrotatable movement of the radiation source.

The container may be made of stainless steel, carbon steel,or equivalent material and it is filled with lead or equivalent radiation absorption material as is the plug and actuating means. Convenient coupling arrangements may be provided in the connection of the actuating means to the actuating rod as well as the crank to the rotatable plug so that these may be detached and the shield with radioactive source in shielded position may be used as a carrier for transporting the radioactive source. For this purpose recess 37 may be provided with a plug which may be made of stainless steel filled with lead.

When in safety position, the radioactive source is at a center of the shielded mass, i.e. a position providing the desired thickness of shielding material around the source. The mass may be of any convenient shape, e.g. of square or circular cross-section and of sufiicient length to provide the desired shielding.

In view of the foregoing disclosures, variations and modifications thereof will be apparent to one skilled in the art, and it is intended to include within the invention all such variations and modifications except as do not come within the scope of the appended claims.

What is claimed is:

1. In an apparatus adapted to maintain a radioactive source in a shielded safety position and also to move it to a radiation position to permit the emanation of radiation, a combination of a mass of shielding material provided with a bore therethrough adapted to hold an actuating rod consisting of a single rigid member to which rod is attached a radioactive source, means for moving said rod between a position so that the radioactive source is substantially in the center of said mass and a position so that the radioactive source is in radiation position outside of said mass, a second bore within said mass at substantially right angles to the above mentioned bore and provided with a plug of similar shielding material within said second bore, said plug being movable from a position permitting passage of the actuating rod through said second bore to a position preventing passage of the actuating rod and radiation through said second bore.

2. In an apparatus adapted to maintain a radioactive source in a shielded safety position and also to move it to a radiation position to permit the emanation of radiation, a combination of; a mass of shielding material provided with a bore therethrough adapted to hold an actuating rod consisting of a single rigid member to which rod is attached a radioactive source; means for moving said rod between a position so that the radioactive source is substantially in the center of said mass and a position so that the radioactive source is in a radiation position outside of said mass; a second bore within said mass at substantially right angles to the above mentioned bore and provided with a plug of similar shielding material within said second bore, said plug being movable from a position permitting passage of the actuating rod through said second bore to a position preventing passage of the actuating rod and radiation through said second bore; wherein said actuating rod is nonrotatable and is adapted to be extended through said second bore out of the shielding and into a receiving aperture wherein it forms part of a level measuring device.

3. In an apparatus adapted to maintain a radioactive source in a shielded safety position and also to move it to a radiation position to permit the emanation of radiation, a combination of; a mass of shielding material provided with a bore therethrough adapted to hold an actuating rod consisting of a single rigid member to which rod is attached a radioactive source; means for moving said rod between a position so that the radioactive source is substantially in the center of said mass and a position so that the radioactive source is in a radiation position outside of said mass; a second bore within said mass at substantially right angles to the above mentioned bore and provided with a plug of similar shielding material within said second bore, said plug being movable from a position permitting passage of the actuating rod through said second bore to a position preventing passage of the actuating rod and radiation through said second bore; wherein said actuating rod is non-rotatable and is adapted to be extended through said second bore out of the shielding and into a receiving aperture wherein it forms part of a level measuring device; and wherein said plug is provided with a bore adapted to be aligned with the first bore and is rotatable and provided with rotating means adapted to turn it from a position where its bore is in alignment with the bore in the fixed mass, in which the actuating rod travels, to a position at a angle thereto.

4. In an apparatus adapted to maintain a radioactive source in a shielded safety position and also to move it to a radiation position to permit the emanation of radiation, a combination of; a mass of shielding material provided with a bore therethrough adapted to hold an actuating rod to which rod is attached a radioactive source; means for moving said rod between a position so that the radioactive source is substantially in the center of said mass and a position so that the radioactive source is in a radiation position outside of said mass; a second bore within said mass at substantially right angles to the above mentioned bore and provided with a plug of similar shielding material within said second bore, said plug being movable from a position permitting passage of the actuating rod through said second bore to a position preventing passage of the actuating rod and radiation through said second bore; wherein said actuating rod is non-rotatable and is adapted to be extended out of the shielding and into a receiving aperture wherein it forms part of a level measuring device; wherein said plug is provided with a bore adapted to be aligned with the first bore and is rotatable and provided with rotating means adapted to turn it from a position where its bore is in alignment with the bore in the fixed mass, in which the actuating means travels, to a position at a 90 angle thereto; and wherein said-rotating means is a pneumatic arrangement including a piston and cylinder adapted to be actuated by compressed air.

5. In an apparatus adapted to maintain a radioactive source in a shielded safety position and also to move. it to a radiation position to permit the emanation of radiation, a combination of; a mass of shielding material provided with a bore therethrough adapted to hold an actuating rod to which rod is attached a radioactive source; means for moving said rod between a position so that the radioactive source is substantially in the center of said mass and a position so that the radioactive source is in a radiation position outside of said mass; a second bore within said mass at substantially right angles to the above mentioned bore and provided with a plug of similar shielding material within said second bore, said plug being movable from a position permitting passage of the rod through said second bore to a position preventing passage of the actuating rod and radiation through said second bore; wherein said actuating rod is non-rotatable and is adapted to be extended out of the shielding and into a receiving aperture wherein it forms part of a level measuring device;- wherein said plug is provided with a bore adapted to be aligned with the first bore and is rotatable and provided with rotating means adapted to turn it from a position where its bore i in alignment with the bore in the fixed mass, in which the actuating means travels, to a position at a 90 angle thereto; wherein said rotating means is a pneumatic arrangement including a piston and cylinder adapted to be actuated by compressed air; and wherein said radioactive source actuating means is provided with a pneumatic actuating source including a piston and cylinder actuating assembly adapted to be actuated by compressed air.

6. In an apparatus adapted to maintain a radioactive source in a shielded safety position and also to move it to a radiation position to permit the emanation of radiation; a combination of; a mass of shielding material provided with a bore therethrough adapted to hold an actuating rod to which rod is attached a radioactive source; means for moving said rod between a position so that the radioactive source is substantially in the center of said mass and a position so that the radioactive source is in a radiation position outside of said mass; a second bore within said mass at substantially right angles to the above mentioned bore and provided with a plug of similar shielding material within said second bore, said plug being movable from a position permitting passage of the actuating rod through said second bore to a position preventing passage of the actuating rod and radiation through said second bore; wherein said actuating rod is non-rotatable and is adapted to be extended out of the shielding and into a receiving aperture wherein it forms part of a level measuring device; wherein said plug is provided with rotating means adapted to turn it from a position where its bore is in alignment with the bore in the fixed mass, in which the actuating means travels, to a position at a 90 angle thereto; wherein said rotating means is a pneumatic arrangement including a piston and cylinder adapted to be actuated by compressed air; wherein said radioactive source actuating means is provided with a pneumatic acv tuating source including a piston and cylinder actuating assembly adapted to be actuated by compressed air; and wherein said actuating rod is substantially square in cross section and travels in a bore at least a part of which is substantially square and is reasonably close fitting therein.

7. In an apparatus adapted to maintain a radioactive source in a shielded safety position and also to move it to a radiation position to permit the emanation of radiation, a combination of: a mass of shielding material provided with a bore therethrough adapted to hold an actuating rod to which rod is attached a radioactive source; means for moving said rod between a position so that the radioactive source is substantially in the center of said mass and a position so that the radioactive source is in a radiation position outside of said mass; a second bore within said mass at substantially right angles to the above mentioned bore and provided with a plug of similar shielding material within said second bore, said plug being movable from a position permitting passage of the actuating rod through said second bore to a position preventing passage of the actuating rod and radiation through said second bore; wherein said actuating rod is non-rotatable and is adapted to be extended out of the shielding and into a receiving aperture wherein it forms part of a level measuring device; and wherein said plug is adapted to be lifted out of the bore to permit the source to move out of the mass.

8. In an apparatus adapted to maintain a radioactive source in a shielded safety position and also to move it to a radiation position to permit the emanation of radiation, a combination of; a mass of shielding material provided with a bore therethrough adapted to hold an actuating rod to which rod is attached a radioactive source; means for moving said rod between a position so that the radioactive source is substantially in the center of said mass and a position so that the radioactive source is in a radiation position outside of said mass; a second bore within said mass at substantially right angles to the above mentioned bore and provided with a plug of similar shielding material within said second bore, said plug being movable from a position permitting passage of the actuating rod through said second bore to a position preventing passage of the actuating rod and radiation through said second bore; wherein said actuating rod is non-rotatable and is adapted to be extended out of the shielding and into a receiving aperture wherein it forms part of a level measuring device; wherein said plug is adapted to be lifted out of the bore to permit the source to move out of the mass; and wherein the plug is provided with pneumatic means for lifting it and mechanical means for holding it in lifted position.

References Cited by the Examiner UNITED STATES PATENTS 2,872,587 2/1959 Stein 250-106 3,026,414 3/1962 Commins 250-106 3,088,032 4/1963 Brunton 250-106 I FOREIGN PATENTS Ad. 71,328 12/1959 France.

858,388 1/1961 Great Britain.

RALPH G. NILSON, Primary Examiner.

ARCHIE R. BORCHELT, Examiner. 

1. IN AN APPARATUS ADAPTED TO MAINTAIN A RADIOACTIVE SOURCE IN A SHIELDED SAFETY POSITION AND ALSO TO MOVE IT TO A RADIATION POSITION TO PERMIT THE EMANATION OF RADIATION, A COMBINATION OF A MASS OF SHIELDING MATERIAL PROVIDED WITH A BORE THERETHROUGH ADAPTED TO HOLD AN ACTUATING ROD CONSISTING OF A SINGLE RIGID MEMBER TO WHICH ROD IS ATTACHED A RADIOACTIVE SOURCE, MEANS FOR MOVING SAID ROD BETWEEN A POSITION SO THAT THE RADIOACTIVE SOURCE IS SUBSTANTIALLY IN THE CENTER OF SAID MASS AND A POSITION SO THAT THE RADIOACTIVE SOURCE IS IN RADIATION POSITION OUTSIDE OF SAID MASS, A SECOND BORE WITHIN SAID MASS AT SUBSTANTIALLY RIGHT ANGLES TO THE ABOVE MENTIONED BORE AND PROVIDED WITH A PLUG OF SIMILAR SHIELDING MATERIAL WITHIN SAID SECOND BORE, SAID PLUG BEING MOVABLE FROM A POSITION PERMITTING PASSAGE OF THE ACTUATING ROD THROUGH SAID SECOND BORE TO A POSITION PREVENTING PASSAGE OF THE ACTUATING ROD AND RADIATION THROUGH SAID SECOND BORE. 